Rehalogenation process of color photography



' colored positive images.

Patented July 15, 1941 UNITED STATES PATENT OFFICE REHALOGENATION raocass or COLOR PHOTOGRAPHY Karl .Schinzel, Zurich, Switzerland, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Original application July 3, 1937,

Serial No. 151,811. Divided and this application December 5, 1940, Serial No. 368,667. In

Austria July 'l, 1936 5 Claims.

aromatic amino coupling developing agent. The

couplers used are those containing a reactive methylene or a phenolic hydroxyl group which reacts with the development product of the aromatic amino developing agent on photographic development to form a colored image. Couplers suitable for incorporation in the emulsion layers are described in my application Serial No. 151,811. A plurality of emulsion layers may be coated on the same support each layer containing the proper coupler for the formation of a colored image upon development. These couplers yield the corresponding colors when the layers are developed with the same developer.

In photographic elements of this type, colored images may be formed either by direct or primary development in a coupling developer or by first developing the layer in a non-coupling developer and then developing the residual silver halide images in a coupling developer to form desirable to form a negative colored image by redevelopment of the silver images formed with a primary non-coupling developer. I have found that this can be accomplished in a multi-layer element in which couplers are incorporated in the silver halide emulsion layers by developing the exposed element in a developer which forms silver images but which does not aflect the couplers, fixing or removing the unexposed silver halide from the layers, reconverting the developed silver images to silver salt images and then coloring the element in a coupling developer to form combined silver and dye images in the layers. This produces negative silver images and complementary dye images corresponding to the negative images.

This method can be used with the customary three-layer element in which three emulsion layers are coated on the same side of a support, the layer nearest the support being red-sensitive, the next layer being green sensitive and the top In certain cases it is layer being blue-sensitive, the yellow filter layer vbeing incorporated between the green sensitive and the blue sensitive layers. The red-sensitive layer preferably contains a coupler capable of producing a cyan image upon coupling development, the green-sensitive layer contains a coupler capable of producing a magenta image upon coupling development, and the blue-sensitive layer contains a coupler capable of producing a yellow image upon coupling development. This threecolor coupling can also be used to advantage if on one side of a thin film the red-sensitive silver bromide emulsion is coated, on the other side a yellow-green-sensitive silver bromide emulsion and above this a highly sensitized silver chloride gelatin emulsion. Three-color coupling can be accomplished in such manner that the silver reduced by an ordinary non-coupling developer, such as ferrous oxalate, is converted after the fixing into silverferrocyanide, silver bromide or silver chloride by means of mercuric chloride.

Primary aromatic amino coupling developers suitable for use in my process include p-aminodi-alkylanilines, such as p-amino-dimethylaniline, and p-aminophenols.

Any of the n'on-difi'using couplers specified in my application Serial No, 151,811 may be used in the emulsion layers. In redevelopment, the middle layer can contain an insoluble -naphthol derivative of other phenol which produces an insoluble green-blue image in the first development with p-amino-diethylaniline after which the element can be fixed and rehalogenated and the two other layers developed in color and finally the silver washed out and removed. It is also possible to develop the element in the usual manner and convert the primary reduced silver to silver ferrocyanide, then expose the residual silver halide and develop with p-amino-dimethylaniline whereby an indamine is formed only in the middle layer and may be decolorized by acid treatment. In an element of this type the middle layer is red-sensitive and the bottom layer is greensensitive.

' hols or phenols as well as acetoacetic anilide and especially its higher arylides and heterocyclic arylides with dihydrothiotoluidine or arylides with one hydrgxyl group or amino group which can be alkylated, forexample, with ceryl bromide or esteriiled, for example, with cerotic acid chloride. Monoacetic acid benzidide is also suit-' able. The higher aliphatic homologues such as undecyl and palmityl acetic esters and their arylides are especially useful.

The following couplers are especially suitable for use in multi-layer coatings. For producing the cyan dye l-naphthol-3,6-disulfodi-(ZN-methylanilide) or the compound formed by condensing amino-a-naphthols with unsubstituted 2- or 4- positions with palmitic or oleic acid chloride. For the coupler producing the magenta dye, the compounds formed by condensing a phenylmethylpyrazolone, carboxylic, or sulfonic acid chloride with cholestyl amine. cholcstyl alcohol or ceryl alcohol. For the coupler producing the yellow dye, dibenzoylacetylbenzidinide or diacetoacetyl- 1,4-phenylenediamine.

The insoluble couplers or their salts are added to the layers in a quantity of from 3 to 20 grams per liter of gelatino silver bromide emulsion. The developers are used in a to 2% solution with about 5% sodium carbonate or the equivalent amount of weaker alkalies. The insoluble components are, if necessary, dispersed in a gelatin solution with the aid of a colloid mill and this emulsion added to the gelatino silver halide emulsion.

I claim:

1. A method of processing a photographic material comprising a plurality of superposed silver halide emulsion layers containing color-forming components to produce differently colored images in the different layers comprising developing the latent image in all or said layers with a developer incapable of afiecting the said coloriormers, removing the unafiected silver halide from said layers, converting the developed silver images into silver salt images which are capable of redevelopment and developing said silver salt images with a developer, the oxidation products of which are capable of reacting with the said color-iormers to produce differently colored images in the layers.

2. A method of producing a non-reversed color record on a photographic material comprising superposed silver halide emulsion layers sensitive to diiierent spectral regions and containing colorof the colored images in said layers which consists in developing the latent images in said forming components to partake in the production emulsion layers to silver with a developer which does not affect the color-formers, removing the unaffected silver halide from said layers, converting the developed silver images into developable silver salt images and then developing said silver salt images to different colors by a single treatment with a developer the oxidation products of which are capable of reacting with the said color-formers to produce colored images in the different layers. 4

3. A method of producing a multi-color photographic record by a process which does not include reversal on a photographic material comprising several superposed emulsionlayers containing color-forming components adapted to react with a paraphenylenediamine developer which consists in developing silver images in all of said layers with a developer which does not afiect the color-forming components, removing the unaffected silver halide from said layers, converting the developed silver images into redevelopable silver salt images and redeveloping the material in a paraphenylenediamine developer to produce differently colored images in all of said layers.

4. A method of producing a non-reversed multi-color photographic record on photographic material comprising a plurality of superposed silver halide emulsion layers containing colorforming components which consists in developing silver images in all of said layers, removing unailected silver halide in said layers, converting said silver images into developable silver salt images, developing the latter images in a developer capable of reacting with said color-forming components to produce differently colored images in said layers and finally removing developed silver from said layers.

5. A method of producing a non-reversed multi-color photographic record on photographic material comprising a plurality of superposed silver halide emulsion layers containing color-forming components which consists in developing silver images in all of said layers, removing the unaffected silver halide from said layers, converting the developed silver images into silver term-cyanide and developing the latter images with a developer capable of reacting with the color-forming components to produce differently colored images in said layers.

KARL SCHINZEL. 

